Maternal and Child Health Bureau ~ 11
5. Body Mass Index-for-age
A recent report by the Surgeon General cited obesity as a major concern among adults with mental retardation, and underscored the need to prevent obesity and increase physical activity. (Satcher, 2001.)
Body mass index-for-age is the recommended method of screening for overweight and obesity, as well as for risk of overweight in children 2-20 years.
Conditions, such as trisomy 21, spina bifida, and cerebral palsy are commonly associated with reduced growth in length and/or stature compared to that of typically-developing children (Cloud, 1997; Scott, 1997; Ekvall, 1993). Weight gain of children with reduced linear growth may be similar to typically-growing children; this increases the potential for problems with overweight. Prevention and management of overweight in children with special health care needs is often a large component of the medical plan. Thus, detection of risk for overweight is critical, and the use of BMI-for-age can be very helpful.
Differences in bone size and fat and muscle distribution make the use of the reference data for many estimators of body composition inappropriate for many children with special health care needs. For example, BMI-for-age may not identify overweight in some children who are "overfat" because of decreased muscle mass.
Since the body composition of a child with special health care needs may differ from that of the reference population, skinfold measurements, along with BMI-for-age, may provide additional critical information about a child's body composition. This information can be useful for monitoring changes in an individual's body composition and growth pattern.
Example: Body Mass Index-for-age
JS is a 10 year old girl with trisomy 21. Her growth charts indicate the following:
Weight-for-age has increased from below the 5th percentile at ages 6 1/2 years and 8 years to between the 25th and 50th percentiles at age 10 years.
Stature-for-age has been consistently below the 5th percentile.
BMI-for-age has increased from close to the 25th percentile at ages 6 1/2 years and 8 years to between the 90th and 95th percentiles at age 10 years.
This information is shared with JS's parents, along with concerns that JS is at risk for overweight. A referral is made to a registered dietitian who has experience working with children with trisomy 21. JS's food pattern is modified slightly, and after six months, her rate of weight gain has slowed, and his BMI-for-age is more appropriate.
Read more about skinfold measures
Skinfold measures can provide information about an individual's body composition. One of the most commonly used skinfold measurements is triceps skinfold. Along with mid-upper arm circumference, this measurement can used to estimate arm fat and arm muscle area. Subscapular skinfold measurements are also useful for estimating fat stores.